This invention relates to the sizing or dressing of fibers, filaments, and yarns whether of spun or continuous filament type, to render such textile materials amenable to textile operations, for example, twisting, doubling, weaving, knitting, braiding and so forth. It is particularly concerned with sizes of the removable type which are adapted to be applied to polyester yarns and especially yarns for use in water jet looms.
Various water-soluble or highly water dispersible polymeric colloidal substances, such as starch, polyvinyl alcohol and acid rich acrylic copolymers have been used for the sizing of yarns including moderately hydrophobic yarns such as nylon yarn, but such materials generally show insufficient adhesion to the more hydrophobic yarns such as polyester. This lack of adhesion requires the application of excessive amounts of sizing material to protect the filaments or fibers or to compensate for the tendency for the size to rub off on guides and other surfaces of the textile fabricating machinery. A suitable polymeric size must not be so hard or brittle as to shed particles during passage through the textile fabricating machinery nor adhere to the metal in preference to the fiber or yarn and in this way lead to deposits of size materials being left on metal drives or drying drums during the processing. Sizing of yarns for use in water jet looms presents particular problems because the shed opening on the looms is very small and electronic controls may be so fine that fuzzy yarns either transfer with the jets or tend to trip the stop motion in electronically controlled units which stop the loom abruptly.
The acrylic copolymer size of the instant invention has excellent adhesion to polyester yarn and does not require extremely stringent drying conditions in order to develop good water resistance. Despite being highly hydrophobic, the polymer is readily removable with a mild alkaline scour and thus is an excellent warp size for polyester yarns to be woven on a water jet loom, or on a conventional shuttled or shuttleless loom. Additionally, the polymer is tack-free in film form and being a latex emulsion, as prepared, it is readily amenable to dilution and dries easily under moderate conditions to a water-resistant tack-free polymer.